Manufacture of thiocarbamyl chlorides



Patented Apr. 5, 1949 MANUFACTURE OF THIOCARBAMY L CHLORIDES Edmond .l'.Bitter, Wyandotte, Mich., assignor to Sharples Chemicals Inc., acorporation of Delaware No Drawing. Application February 2, 1946, SerialNo. 645,233

Claims. 1

heretofore been made by reaction of thiophosgene with amines, but thisreaction does not provide a satisfactory procedure, in view of the factthat the thiophosgene is too difficult and expensive to make toconstitute a satisfactory starting material.

The present invention rests upon the discovery that the thiocarbamylchlorides can be made by the relatively simple procedure of chlorinatingthe corresponding thiuram sulfides. The thiuram sulfides which can betreated most effectively in practice of the invention may be representedby the following formula:

in which at is an integer and R1, R2, R3 and R4 are hydrocarbonsubstituents. R1, R2, R3 and R4 may be either alkyl or arylsubstituents, but R2 and R4 will ordinarily be alkyl substituents incases in which R1 and R3 are aryl substituents. The symbols R1 and R2may represent between them a single polymethylene radical such aspentamethylene, and the symbols R3 and R4 another such radical. Thus,the compounds which may be successfully chlorinated in practice of theinvention include tetra-alkyl, symmetrical di-alkyl-di-aryl, anddi-polymethylene thiuram sulfides. In the chlorination of compounds ofany of these types in the practice of the invention, there is asplitting of the thiuram sulfide and combination of chlorine with thethiocarbamyl radical to form the corresponding thiocarbamyl chloride, asindicated by the following equation, which illustrates the splitting andchlorination of a disulfide.

R R R \N-GSSGN/ +013 2 \NCCI+2S l l R R i In order to facilitate anunderstanding of the invention, it will first be described withreference to a typical operation by which tetra-ethyl thiu- Thetetra-ethyl thiuram disulfide may be placed in a flask which is immersedin a hot water bath until melted. Chlorine gas may then be introducedbeneath the surface of the melted thiuram sulfide product intermittentlyover a period of 15 minutes until half of the amount of chlorinenecessary to effect the desired chlorination has been added. If thetemperature at the beginning of the chlorination procedure is 75 C.,this temperature may rise to 82 C., for example, during introduction ofthe chlorine. The flask may then be immersed in a water bath maintainedat 40 C. and chlorination continued until the theoretically necessaryquantity of chlorine has been added, the temperature being maintainedbetween and C. during this continued chlorination. After thechlorination reaction has been completed, the reaction product ispreferably maintained at a temperature between 50 and C. for two hoursor longer to permit sulfur and a trace of amine hydrochloride toprecipitate. The product may then be filtered at a temperature of 52 0.,and the filtrate distilled under vacuum to yield di-ethyl thiocarbamylchloride of a high degree of purity.

While chlorination of various substituted thiuram sulfides such asrepresented by the above formula and equation may be accomplished bydirect treatment of the liquid or melted thiuram sulfide, just as in thecase of the tetra-ethyl thiuram disulfide discussed above, it will bedesirable in many instances to suspend or dissolve the particularthiuram sulfide to be treated in a suitable solvent or diluent which isrelatively inert under the conditions of the reaction. Thus, the thiuramsulfide maybe suspended in carbon tetrachloride or dissolved in benzeneor chloroform, and then subjected to chlorination by introduction of astream of gaseous chlorine or other chlorinating agent providing freechlorine.

The chlorination reaction may be performed upon thiuram sulfides ofvarious degrees of sulfur content. Thiuram mono-sulfides, tri-sulfidesor tetra-sulfides may, for example, be chlorinated in the same manner asthe corresponding disulfides, the only difference in chlorination ofthese other sulfides being that, in the case of the mono-sulfide, only asingle molecule of the desired thiocarbamyl chloride is formed by thechlorination, and in the case of triand tetrasulfides, a larger quantityof sulfur is liberated incident to formation of two molecules ofthiocarbamyl chloride from a single molecule of the thiuram sulfide thanis the case in chlorination of the disulfide. While the various thiuramsulfides may be chlorinated under the conditions discussed above in amanner closely analogous to that discussed by way of illustration withrespect to chlorination of tetra-ethyl thiuram disulfide, it should beunderstood that a wide variety of conditions may be adopted in practiceof the invention, both with respect to chlorinating agent, conditions ofthe reaction and material to be chlorinated. The following examplesillustrate a number of variants which may be adopted in practice of theinvention.

Example I 402 grams (1.36 moles) of tetra-ethyl thiuram disulfide weredispersed in 800 ml. of carbon tetrachloride. 96.5 grams (1.36 moles) ofchlorine gas were bubbled into the resulting suspension over a period ofabout minutes, the temperature rising from 32 C. to 67 C. during thisinterval. By the time 49 grams of chlorine had been added, the remainingtetra-ethyl thiuram disuliide had become dissolved, with the result thata clear, reddish brown solution was formed. When 76 grains of chlorinehad been added, the solution became cloudy due to formation of freesulfur. At the conclusion of the chlorination, sulfur was precipitatedby cooling the reaction mixture on an ice bath. One-third of the solventwas then stripped off under vacuum and the solution was kept overnightat about 10 C. to precipitate further sulfur, which was removed byfiltration. One-half of the remainin solvent was then stripped ofi andthe residue was cooled on an ice bath and filtered. 200 grams of yellowcrystals constituting crude di-ethyl thiocarbamyl chloride wereobtained, having a melting point of 48-50 C. The filtrate resulting fromthe preceding operation was then stripped of solvent to give a secondportion of product contaminated with sulfur. This crude product wasremelted at 50 C., and the small quantity of sulfur precipitated in thisremelting operation was removed. Upon solidification of the product, 202grains of a light brown crystalline mass, M. P. 46.5-48.0 C. wereobtained. This material was distilled at 113 C. at 10 mm. Hg. pressure.Analysis showed 23.31% Cl, 8.89% N, 21.01% S. compared to theoreticalvalues of 23.4% C1, 9.2%% N, and 21.1% S. The total yield was 402 gramsor 98%.

Example II 1118 grams (4.65 moles) of tetramethyl thiuram disulfide weredispersed in 3 liters of carbon tetrachloride. 3305 grams 1.65 moles) ofchlorine gas were bubbled into the resulting suspension during a periodof three hours, the temperature rising from 25 C. to 65 C. during thischlorination. No external cooling was provided. The chlorinationreaction resulted in formation of a relatively clear, deep orangesolution. Toward the end of the reaction, the solution became milky, dueto precipitation of sulfur. The flask containing the reaction productwas immersed overnight in a water bath maintained at 10 0., and theproduct was decanted from the large mass of sulfur thus precipitated.The solvent was removed by vacuum distillation and the residue of thisdistillation was maintained at 50 C. for 30 minutes to precipitate afurther small amount of sulfur. 1075 grams of crude dimethylthiocarbamyl chloride (95.3% yield) were then decanted off. Uponpurification, this material was found to have an M. P. of 42.5-43.5 C.

4 Example III 296 grams (0.73 mole) of tetra-butyl thiuram disulfidewere dissolved in 500 ml. of carbon tetrachloride. grams (0.73 mole) ofchlorine gas were bubbled into the resulting suspension over a period or20 minutes. The temperature rose from C. to 45 C. during introduction ofthe first 26 grams of chlorine, and the flask was then immersed in anice bath and the reaction completed by introduction of the remaining 26grams of chlorine to the reaction mixture maintained at about 30 C. Uponremoval of free sulfur and solvent as in the preceding examples, a darkbrown filtrate of crude di-butyl thiocarbamyl chloride weighing 260grams (87% of theory) was obtained.

Example IV 148 grams (0.5 mole) of tetra-ethyl thiuram disulfide weresuspended in 500 m1. of carbon tetrachloride. 67.5 rams (0.5 mole) ofsulfuryl chloride were dissolved in 100 ml. of carbon tetrachloride, theresulting solution was added to the suspension of tetra-ethyl thiuramclisulfide over a period of 25 minutes during continued stirring of thereaction mixture. The resulting chlorination reaction was exothermic,the temperature rising from 25 C. to 36 C. during the course of thereaction. The stirring was continued for additional minutes at roomtemperature, with slow evolution of sulfur dioxide. The material wasthen heated with a low flame for 30 minutes and refluxed for one hour,and allowed to stand overnight at room temperature. About 2 grams ofamorphous sulfur was filtered from the product.

The solvent was removed by vacuum distillation over a hot water bath,leaving a solid crystalline residue upon cooling. This was heated to 60C. and the melted product was decanted from 40 precipitated sulfur,yielding upon coolin 151 grams (99.7% of theory) of crude di-ethylthiccarbamyl chloride, MP. 48-4-9 C.

Example V 208 grams (1.0 mole) of tetra-methyl thiuram mono-sulfide weredispersed in 675 ml. of carbon tetrachloride. 76 grams (1.56 mole) ofchlorine gas were bubbled into the resulting suspension over a period ofone hour, and the temperature rose from 23 C. to 50 C. during the courseof the chlorination. During introduction of the last half of thetheoretical quantity of chlorine, the solution resulting from thechlorination already accomplished was placed on an ice bath, with theresult that the chlorination was completed at a temperature of about 40C. A large quantity of sulfur precipitated at the end of the reaction.Upon removal or" sulfur and solvent as in previous examples, 132.5 grams(53% of theory) of dimethyl thiocarbarnyl chloride were obtained.

Example VI 152 grams (0.5 mole) of tetra-methyl thiuram tetra-sulfideWere dispersed in 500 ml. of carbon tetrachloride. 35.5 grams (0.5 mole)of chlorine gas were bubbled in over a period of 20- minutes, with aresultant rise in temperature from 23 C. to 52 C. This example presenteda contrast to the chlorination of tetra-ethyl thiuram disulfide, as inthe preceding examples, in that a clear solution was not obtained at'anytime during the course of the reaction of the present example, due tosplitting out of free sulfur. Solvent and sulfur were removed as-inpreceding examples, and the resulting di-methyl thiocarbamyl ch1o-,

ride weighed 58 grams (94% of theory), M. P. 41.543.0 0., as compared toa melting point of 42 C. assigned to this compound by Beilstein.

Example VII 148 grams (0.5 mole) of tetra-ethyl thiuram disulfide weredissolved in 500 ml. of benzene. 35.5 grams (0.5 mole) of chlorine gaswere bubbled in over a 15 minute interval, the temperature rising from25 C. to 60 C. Upon removal of sulfur and solvent, 142 grams (93.8% oftheory) of crude di-ethyl thiocarbamyl chloride were obtained.

Example VIII 148 grams (0.5 mole) of tetra-ethyl thiuram disulfide weredissolved in 500 ml. of chloroform. 67.5 grams (0.5 mole) of sulfurmonochloride were dissolved in 100 ml. of chloroform and the resultingsolution was added to the tetra-ethyl thiuram disulfide solution over aperiod of minutes, with continued stirring. The temperature rose from 21C. to 45 C. during introduction of the sulfur monochloride. Theresulting solution was refluxed for one hour at 62 C. and then cooledand filtered. Upon purification as in preceding examples, 119 grams (79%yield) of crude di-ethyl thiocarbamyl chloride were obtained as a lightbrown crystalline material, M. P. 47-495 C.

Example X 148 grams (0.5 mole) of tetra-ethyl thiuram disulfide wereplaced in a flask which was immersed in a hot water bath until thetetra-ethyl thiuram sulfide had melted. No solvent was added. Chlorinegas was bubbled into the melted material intermittently over a period ofminutes until about half of the theoretically required amount ofchlorine had been added. The temperature rose from 75 C. to 82 C. duringthis period. The flask was now immersed in a water bath maintained at 40C., and introduction of chlorine was resumed until the theoreticallyrequired amount of chlorine had been added, the temperature of themelted product being kept between 50 C. and 60 C. during this completionof the chlorination reaction. Sulfur precipitated at the end of thereaction. The melted product was kept at a temperature between 50 C. and70 C. for two additional hours to permit sulfur and a trace of di-ethylamine hydrochloride to precipitate. The melted product was then filteredat 52 C. and cooled to obtain a crystalline mass weighing 142 grams (94%of theory), M. P. 47-49 0.

Example XI 192 grams (0.5 mole) of di-pentamethylene thiuramtetra-sulfide were dispersed in 700 ml. of carbon tetrachloride. 38grams (0.53 mole) of chlorine gas were bubbled in over a minuteinterval, and the temperature rose from 23 C. to 48 C. during thischlorination. A cloudy precipitate was present throughout the course ofthe reaction, due to splitting out of free sulfur.

Upon purification as in preceding examples, '78.

grams (95.3% of theory) of pentamethylene thiocarbamyl chloride wereobtained as an orange oil having a specific gravity at 20 C. of 1.250.The reaction of this example is represented by the following equation:

0112-05 GHQ-CH2 I OH; NCSSS-S-C 0H, 01,

CHz-C g S S CHz-C 2 CHrCHg 2o 2 NCC1+4S CHz-C s Example XII 75.5 grams(0.19 mole) of symmetrical diethyl diphenyl thiuram disulfide weresuspended in 300 ml. of carbon tetrachloride. 13.7 grams (0.19 mole) ofchlorine gas were passed into the resulting suspension over a period ofabout 20 minutes. The temperature rose from 25 C. to 47 C. duringintroduction of the chlorine. Upon purification of the product, 75 grams(98% of theory) of ethyl phenyl thiocarbamyl chloride were obtained inthe form of pale yellow crystals, M. P. 55.5-56.5 C. The reaction ofthis example is represented by the following equation:

C2H5 02B! ZHE NOSSO C1 NCgl 25 00 5 S S C6H5 00115 S Example XIII Into aglass lined vessel Was charged 276 lbs. (0.931 lb. mole) of tetra-ethylthiuram disulfide and 212 lbs. of benzene. The resulting slurry,maintained betweeen 50 and 60 C. and continuously agitated, wascontacted with chlorine gas. 68 lbs. (0.958 lb. mole) of the latter wereintroduced through a partially submerged Well-pipe over a period ofminutes. After cooling the mixture and separating the sulfur whichdeposited, 479 lbs. of solution were obtained, containing 251 lbs. (1.66lb. mole) of diethyl thiocarbamyl chloride. This corresponded to a yieldof 89.3%.

While the invention has been described above in terms of use of gaseouschlorine, the various chlorinating agents capable of liberating freechlorine and being used in non-aqueous media may be employed in practiceof the invention. The following example illustrates use of a mixture ofphosphorous pentachloride and phosphorus oxychloride in this connection:

Example XIV 151 grams of tetra-ethyl thiuram disulfide, 114 grams ofphosphorus pentachloride and '75 grams of phosphorus oxychloride wereplaced in a flask equipped with a reflux condenser and heated by meansof a water bath. After being maintained at a temperature of 95-100 C.for 3 hours the material was distilled under vacuum, 202.5 grams ofyellow oil being taken overhead. The residue, crude diethyl thiocarbamylchloride, which melted at 46-48 C. amounted to 48.1 grams. Thiscorresponded to a yield of 53.5%.

Still further modifications are possible within the scope of theinvention, and I do not therefore wish to be limited except by thefollowing claims.

I claim:

1. In the manufacture of di-alkyl thiocarbamyl chlorides, the processcomprising contacting una der. substantially non-aqueous conditions atetraalkyl thiuram sulfide with chlorine until reaction occurs betweensaid thiurarn sulfide and said chlorine to effect splitting of saidthiuram sulfide and formation of the corresponding di-alkyl thiocarbamylchloride.

2. In the manufacture of pentamethylene t iiocarbamyl chloride, theprocess comprising contacting under substantially non-aqueous conditionsa di-pentamethylene thiuram sulfide with chlorine until reaction occursbetween said thiuram sulfide and said chlorine to effect splitting ofsaid thiuram sulfide and formation of the desired .pentamethylenethiocarbamyl chloride.

3. In the manufacture of di-alkyl thiocarbamyl chlorides, the processcomprising contacting under substantially non-aqueous conditions atetraalkyl thiuram di-sulfide with chlorine until reaction occursbetween said thiuram sulfide and said chlorine to effect splitting ofsaid thiuram sulfide and formation of the corresponding di-alkylthiocarbamyl chloride.

4. In the manufacture of di-alkyl thiocarbamyl chlorides, the processcomprising contacting under substantially non-aqueous conditions atetraalkyl thiuram poly-sulfide with chlorine until reaction occursbetween said thiuram sulfide and said chlorine to effect splitting ofsaid thiuram. sulfide and formation of the corresponding dialkylthiocarbamyl chloride.

5. In the manufacture of di-ethyl thiocarbamyl chloride, the processcomprising contacting under substantially non-aqueous conditionstetraethyl thiuram disulfide with chlorine until reaction occurs betweensaid thiuram sulfide and said chlorine to effect splitting of saidthiuram sulfide and formation of di-ethyl thiocarbamyl chloride.

6. .A process for the production of substituted thiocarbamyl chloridewhich comprises subject'-- ing to the action of a chlorinating agent ina substantially non-aqueous system a thiuram so l-- fide having theformula:

cals' and taken collectively represent a single polymethylene radical,and in which R3 and taken individually represent one of a groupconsisting of alkyl radicals and aryl radicals and taken collectivelyrepresent a single polymeth 8 ylene radical, and continuing the actionof said chlorinating agent until splitting of said thiuram sulfideoccurs with the formation of substituted thiocarbamyl chloride.

7. The process of claim 6 in which the chlorinating agent is chlorine.

8. The process of claim 6 in which a: has a value of from 1 to 4.

9. The process of claim 6 in which each of R1, R2, R3 and R4 is an alkylradical containing from 1 to 4 carbon atoms.

10. The process of claim 6 in which R1 and R2 collectively are apolymethylene radical, and R3 and R4 collectively are a polymethyleneradical.

11. The process of claim 6 in which the chlorinating agent is chlorine,in which a; has a value of from 1 to 4, and in which each of R1, R2, R3and R4 is an alkyl radical containing from 1 to 4 carbon atoms.

12. The process of claim 11 in which the reaction takes place in thepresence of a diluent which is substantially inert under the conditionsobtaining in the Zone of the reaction.

13. The process of claim 6 in which the chlorinating agent is chlorine,in which a: has a value of from 1 to 4, and in which R1 and R2collectively are a polymethylene radical and R3 and R4 collectively area polymethylene radical.

14. The process of claim 13 in which the reaction takes place in thepresence of a diluent which is substantially inert under the conditions0btaining in the zone of the reaction.

15. The process of claim 6 in which the reaction takes place in thesubstantial absence of a diluent but with the thiuram sulfide in liquidphase.

EDMOND J. BITTER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS

